The present invention relates to a positioning hinge, particularly to a positioning hinge for pivoting between a main unit and an LCD display of a portable computer or electronic dictionary, which can adjust the pivot orientation of the LCD display.
LCD displays of conventional portable computers are generally pivotally assembled on main units by a pair of hinges. U.S. Pat. No. 6,108,868 issued on Aug. 29, 2000 to Davys Lin discloses a positioning hinge having a cam block and a resilient friction member mounted on a pivotal base. The resilient friction member resiliently presses against the surface of the cam block to achieve the purpose of adjusting the orientation of the LCD display relative to the main unit. It is true that the ""868 patent successfully achieves its predetermined purposes. However, because its resilient friction member is mounted on the pivotal member, the friction between the resilient friction member and the cam block has an undesirable, sudden change due to the complicated contour of the cam surface. That is, as the peripheral surface of the cam block diminishes in diameter, the friction force will be greatly reduced at the same time. This results in an unsmooth swinging of the LCD display. In details, the torsion spring constantly has a great torsion force during the swinging of the LCD display. When the LCD display suddenly stops due to the pivot positioning effect, the great torsion force in the torsion spring will shake the main unit and the LCD display due to the inertia in the display. In view of this defect, there is a need to provide an improved positioning hinge having a cushioning mechanism so as to obtain a relatively longer life.
The object of the present invention is to provide an improved positioning hinge having the following advantages: (a) it provides a resilient swinging operation to the LCD display; (b) it allows a user to adjust the orientation of the LCD display when the display is resiliently swung to a predetermined viewing angle so as to adapt to ambient lighting; (c) it provides a smooth swinging operation to the LCD display so as to correct the positioning defects between the main unit and the display; and d) it provides a cushioning mechanism to the friction structure so as to reduce the wear between the hinge components.
To achieve the above intended purposes, the positioning hinge according to the present invention essentially comprises a pivotal member, a pivotal base, a first torsion spring and a friction device.
According to one embodiment of the present invention, the pivotal member is secured to a main unit and has a rotary shaft having a rotary axis. The pivotal base is secured to the LCD display and essentially includes a first support through which the rotary shaft passes so that the rotary shaft can pivot thereabout. The torsion spring has two ends which bias against the pivotal member and pivotal base, respectively, thereby providing a torsion force to allow the pivotal base to rotate with respect to the pivotal member so as to result in a relative pivotal movement between the display and the main unit. The positioning element formed with a friction surface is non-rotatably installed around the rotary shaft. The resilient compression member includes a slide-friction member and a resilient mechanism, wherein the resilient mechanism is provided between the pivotal base and the slide-friction member so that there is always a cushioning frictional contact between the slide-friction member and the positioning member.